The proof of both theorems can be found in [1]}
or in [2]}. We remark that given \(f\in \mathfrak {S}\)  we
have
\(\gamma =\lim _{z\rightarrow \infty }f(z),\qquad \sigma (x)=\displaystyle \frac{1}{\pi }\lim _{y\rightarrow 0^{+}}\mathfrak {Im}f(x+iy),\) 
